Door panel question

I have a few questions. I'm looking to do some pods and paint my door. I have a '96 Ford escort . Anyhow. I would like to take the grey/multi-colored stripe carpet completely off. And in the same area as the stock speaker, I want to put a pod with the mid's facing me. My question is, with the carpet removed, will the fiber-board base the carpet is attached to be adequate for fiberglass? I just need to put the rods and ring for the mid mount, stretch the fiber and have at it.

My next question, I want to put the tweeters by the door handles, as there is perfect room. The problem here is it is all vinyl, and the door handle/tweeter are juts away from the base of the door panel. How could I put a base for the fiberglass and ring, while retaining structural integrity? And would sanding the vinyl down to a smooth texture, prime it with the fiberglass'd section, be adequate in making it look flush?